1. Field of the Invention
The present invention relates to a magnetic sensor that uses a magnetoresistive effect element used as, for example, a geomagnetic sensor.
2. Description of the Related Art
A magnetic sensor that uses a magnetoresistive effect element can be used as, for example, a geomagnetic sensor configured to detect geomagnetism and mounted in a mobile apparatus such as a cellular phone. In the magnetoresistive effect element, an electrical resistance value changes in response to the magnetic field intensity in a sensitivity axis direction.
As disclosed in Japanese Unexamined Patent Application Publication No. 2005-183614, a magnetoresistive effect element includes a plurality of element units (magnetoresistive effect layers 6 in Japanese Unexamined Patent Application Publication No. 2005-183614) and permanent magnet layers connecting the ends of the element units to each other and has a meandering shape. The magnetoresistive effect element is formed in a meandering shape because an element with a large length has a large element resistance and thus power consumption can be reduced.
However, the magnetic sensor having the above-described structure poses the following problems.
As shown in FIG. 13, the number of times the element units 40 are made to reverse direction using permanent magnet layers 41 is increased and thus a magnetoresistive effect element that excessively extends in a sensitivity axis direction (a fixed magnetization direction (P direction) of a fixed magnetic layer) is formed. In particular, as shown in FIG. 14, when the magnetic sensor is used for detecting a magnetic field in the height direction (Z direction) of a geomagnetic sensor, the magnetoresistive effect element is formed so as to extend in the height direction, which is a sensitivity axis direction. Therefore, there is a problem in that the thickness T6 of a Z axis magnetic field detection unit 42 in the height direction is excessively increased.
Furthermore, if the individual element units 40 are formed so as to have a large length in the element-length direction (longitudinal direction), a bias magnetic field generated from the permanent magnet layers 41 disposed on both sides of the element units 40 in the longitudinal direction does not effectively act around the center of each of the element units 40. As a result, hysteresis occurs and the linearity of the ratio (MR ratio) of change in resistance to an external magnetic field in the sensitivity axis direction tends to decrease.